Action limps to BB who silently replaces his BB with an overchip: call or raise?

[MikeB]

Interesting case posted recently on Twitter:

NLHE, 2.5/5k blinds. Called around to the BB who on his option pulls back the 5k and silently tosses out a 25k chip.

Call or raise?

[Nick C]

Is this a trick question? In my card room...it's a raise.

[Uniden32]

I agree, definitely a raise.

[Brian Vickers]

This example was brought up at summit and was overwhelmingly agreed up that it should be a raise.  There is no other logical reason for the BB to do this at this point when facing the option to check or raise.  The manipulation of previously wagered chips in this case was enough indication of the player's intent to raise.