RyGuy
High Hand
Good morning, everyone! Sleepy eyes here after a .25/.50 game that ended at 2 AM. 
As a proud rule stickler, I actually wasn't sure what to do in this situation that happened last night. No big controversy or anything--just didn't know the answer and am hoping you can set me straight. Assuming we play the standard rules that a single chip is a call, and raises are double the raised amount...
.25/.50 blinds
UTG makes it $2.50
Folds to BB who adds a $5 chip to his .50 without saying anything (he had only $5 and .25 chips in his stack), totaling $5.50 in the pot using three chips.
Is this a call or a raise?

As a proud rule stickler, I actually wasn't sure what to do in this situation that happened last night. No big controversy or anything--just didn't know the answer and am hoping you can set me straight. Assuming we play the standard rules that a single chip is a call, and raises are double the raised amount...
.25/.50 blinds
UTG makes it $2.50
Folds to BB who adds a $5 chip to his .50 without saying anything (he had only $5 and .25 chips in his stack), totaling $5.50 in the pot using three chips.
Is this a call or a raise?