In Short:

Yes. It happens often.
It's usually not a warning sign, but a sign that something is irritated or not properly clean.

Why We Consider This Normal:

Itching is considered embarrassing, so we ignore it.
Or we accept it as part of going to the toilet, like toilet-paper dust or red pressure marks. No one asks out loud whether it actually has to be that way.

The Honest Explanation:

After a bowel movement, more is often left behind than you'd think: moisture, residue, friction.
Toilet paper dries out, scratches, and spreads things around. The skin there is thin and reacts quickly.

Itching doesn't happen because something is "wrong," but because the skin is irritated.
Too much wiping, too little cleaning, sweat, or small bits of residue are enough to cause it.

Is That True?

"Itching means I'm not clean."
Not necessarily. It usually means: the skin is stressed.

"It's because of bad food."
Sometimes. Often it's simply friction and dryness.

"This is a medical problem."
Only rarely. Usually it's everyday and harmless.

"Everyone else doesn't have this."
Yes they do. They just don't talk about it.

Our Take:

When something itches regularly, ignoring it isn't a solution.
Cleanliness should soothe, not irritate further.

Putting It in Context:

Pay less attention to perfection.
More to how your skin feels afterward.