A decree can be modified but only for reason of cause, not just becasue one party or the other is not happy with the decree.
Normally a person would have to prove that the other person lied about a significant issue, such as hidden marital assets or hidden current income levels. Since a divorce is normally just about splitting of maritial property the issue outstanding would normally be about hidden money (not a few dollars) at a significant level.
Ex is hiding money and to save himself he decided to file modification. He doesn't like the decree now after 6-7 years because it is benefiting me. I filed a countersuit that he was supposed to pay that money to me but kept it knowing full well he is wrong.
Can you legally prove that he is hiding money? If you can than make sure you obtain this information legally prior to the motion for modification.
After 6-7 years, if you have not failed to disclose information, you will be fine. On the other hand you may want to also file the same if indeed you can prove that he has hidden income you were entitled to recieve. I would just let it go and move on and am really not sure wy after so many years he is even thinking about messing with you, as far as he is concerned you two are divorced and no longer have anything in common.