Why did a gate officer and exit immigration officer try to peel my visa sticker?

I am a citizen of a south asian country who recently travelled to Spain on a Schengen visa for a job interview. My flight was via Dubai (DXB), and the gate officer unsuccessfully attempted to peel off the Schengen visa stamp before letting me onto the plane. On arrival to Spain, I was able to breeze through passport control, perhaps within 15 seconds of being called to the counter.

However, when I was exiting Spain, the passport control officer (at the same airport where I entered) again attempted to peel the sticker off, then put my passport under a UV light, questioned me and let me back onto a plane to DXB.

I have two main questions:

• Is attempting to peel the visa off expected behaviour? Is there any chance that a legitimate visa sticker could get peeled off or be damaged in this process?

• Why did I face 'enhanced' passport control at exit? If I had a forged visa, isn't the point moot if I'm travelling back to my home country? I did have a multiple entry visa, but even if that triggered the extra check at exit, wouldn't it make more sense to do this on entry?

–——————

Follow-up questions.
I'd have used my normal account, but I preferred to ask this anonymously.

@o.m. replied:

Most likely they wondered if your visa was a fake, but concluded that their initial impression was wrong.

• Does the gate officer (for Emirates, in this case) have authority to possibly tamper with my passport?

• Since o.m. didn't answer this, what about any damage that might be caused to the passport or the visa sticker?

• This is a side question, and won't affect me marking any answer below as accepted, but how does the consulate stick the visa so that it won't come out as easily?