Yes, mine developed a split. Having no idea what to do, I asked a wood working friend. He advised to carefully open the crack just a little bit, inject epoxy from the inside only, squeeze together and quickly remove any excess epoxy on the outside of the forend. I used a hypodermic syringe with a short needle. The epoxy is holding and I've had no further problems. You might have a diabetic friend who'll give you an old syringe and needle.
The other option is to replace it. Numrich has it in stock.
Part# 577980 Forend, 12 Ga., 11' OAL, For Models w/ Counter Recoil Gas System. $98.50. I bought one just to have a spare.
My receiver also developed a very small crack at the rear of the ejector port. Several guys on this site advised to drill a very small hole at the back end of the crack. I did, problem solved as the crack has not gotten any larger.
Several 870 Comp shooters on this site also said to make sure the forend nut is as tight as you can get it in order to prevent receiver and forends cracks.
Tom: Take the wood off the metal completely, then follow Skrap Shooters advice, stretch a couple rubber bands around it for half an hour or so, works fine and it won't split there again, beside it maybe but not in the epoxy. Ross