There is a balance between maintaining point of view, and maintaining suspense, which can crop up whenever your protagonist or your POV (point-of-view) character is planning ahead in any detail.
The difficulty is this: If in your story your POV character is making plans and preparations, and then afterwards he puts those plans and preparations into action, then the reader has to wade through the same essential scene twice: first in planning, then in practice. That means that the important scene, the action scene where everything's on the line, is at risk of feeling repetitive and dull.
If we stick purely to good POV practice, then the reader should really know anything important that the POV character knows. Doing otherwise creates distance between the reader and the character, and makes the reader more aware of the author's artifice and manipulation. But that means we simply can't have a story where the POV character plans something of any importance and then carries it out (or even some of it).
A really common example is heist stories. If there's a detailed scene laying out the plan before a heist attempt, then inevitably the plan gets messed up really early, so the plan we already know is tossed out the window. But if the planning stage is skipped over or cut past, that's because the execution of the plan needs to be suspenseful, which means they can't tell us most of the plan yet.
So, information-hiding of this type is kind of a cheat or a compromise, sacrificing point-of-view consistency in order to create suspense. It's a commonly-used technique, and readers are used to it, and will usually not object. It's particularly helpful if the reader knows the information being hidden is going to be revealed to him, and fairly soon - for example, if the heist gang leader says "OK, here's the plan," and then we launch right into the actual heist scene, where the plan is carried out. In this case, it's clear to the reader that's the characters know more then he does, but it's also clear why this information was hidden, and the information is about to be shared (by showing, not telling! :) ).
In mysteries, information-hiding serves the same purpose - to keep up suspense that we wouldn't have if we knew everything the POV knows. It carries the same price - it hurts POV, it feels artificial, the reader feels as if he's being toyed with and strung along.
You'll have to judge each case individually, mostly to see how big a breach of POV it is. In general, I would avoid leaning on information-hiding if possible, but I wouldn't hesitate to use it when it's the right tool for the job.
When you do use it, you want to minimize the damage. Let your protagonists have one or two mysteries; don't have huge swaths of the story the readers constantly feel shut out of. Know what other contracts you're committed to; if you're writing a fair-play mystery, then it's OK for the detective to know things the reader doesn't, but you've still got to write fair-play and actually provide all the clues.
A different, well-known solution to the problem is to create a Watson, a sidekick-ish character who naturally isn't privy to all the details and planning, who serves as the narrator. This lets the detective detect, and know far more than the reader, without breaking the Watson's POV (because Watson knows what we do, not what the detective knows).