Tilde key (~) tabs to transient for some reason

Hi there, simple question,

Sometimes my tilde key works properly as expected (to switch between slip, grid shuffle and spot modes).
However sometimes for an unknown reason it behaves as if it was the TAB key.
I will push "~" in order to switch from grid to slip mode and suddenly I have tabbed over to a transient, or to the beginning of the next clip in my timeline. Wtf?

Thanks in advance! :-)