Rock, welcome to the Forum !
Sounds like you scraped over something, and knocked it loose.
I'd cut it out, maybe a swatch of about 1.25x11", just enough to get the whole place opened up.
Could be there may have been some residual sap lingering in the wood, before you put the FG on originally.
You might get some Turpentine, wash it good, and let it dry completely (24+hrs). Then make sure you get a good coat of Resin on the wood, before you cap it off with the FG and another coat.
And yea, you'll be able to see the patch, but, the only other way is to re-do the whole bottom of the craft, sorry!
Have a good Day !
S.W.
PS: Don't drink and drive !