Allies causing forced flag drop?

I dropped the flag in wsg after a paladin decided to cast something on me, I didn't catch what it was but I think it was Hand of protection. Is it supposed to do that?

It's a bit messed up because he can grab the flag off of an ally right before capping and get the hp bonus, while someone else does the work of getting it to base.

Yes this worked in WotLK, was nerfed in some later expansions.

Yep. HoP will make you drop the flag.
That's how I got Ironman achievement on my pala :^)

Thank you for your responses.