That's the front end of the 178. The panels do not always sit perfectly and the notches are nail marks from assembly (the patching isnt always done very well.
I don't think it it anything to worry about but there are a few things to look for on the 178
1. check to see if there are any leaks (or water stains from earlier leaks) around the push-out
2. check to see if there are any leaks from the external storage doors
3. the spoiler is the black add on above the back window, these are notorious for warping in the heat and require significant sealant above them. Get a ladder and check the sealant to make sure there are no open areas or cracks
4. check all caulking / sealant on the roof
5. make sure the drainage pipes are secure (along the "drivers side' of the trailer)- the brackets are not well designed
I've had a 178 for a few years now and absolutely love it. There will always be craftsmanship issues, but you're going to get that in any trailer
Enjoy!