Question about transom rot
 

Pythons are similar to panteras, so have a question about possible transom rot. How can you detect it? Also, the python is a 1997 24 with an HP 500 in it. No stress cracks, etc. Just some minor knicks on botom of hull at the front of the boat. One gash on the bottom that would need to be patched that just goes through the gel and has exposed the glass. Boat has 174 hours on it. Looks like it is in good condition, etc. Some minor blemishes here and there, etc. Boat has been in storage for the past 4-5 years and has had 30 hours put on it. Noted a dried mushroom on the right SS exhaust at the transom. It is on the left/top side of the SS exhaust/transom. Knocked around the transom, etc., but it seemd solid. Only thing I noted was the mushroom. Engine looks clean, etc. Starts right up and runs great. Was not able to put it in the water, as it was raining. Wondering if this may be possible transom rot or just from being in st :( orage for so long and being put away after being in the water, etc. Any feedback would be greatly appreciated.