Q:  5.27.20  2:24 am huh? isn't the 9 C#?
A: i was assuming +9 means 'augmented 9' or 'sharp 9'. You may have assumed it means "add9", but if it's add 9, it really shouldn't say + because that is a symbol for augmented, and also, because it was Bm7, it also includes the 7, and "add9" usually means you add 9 without having the 7. where as if you wanted to keep the 7 it would be just Bm9. Also, possibly, this confusion could have been avoided by saying Bm7(#9). But according to my best reasoning, i determined that it was nearly 100% likely that the person meant aug9 or sharp9 and not 'add 9', based on all the charts i have seen throughout my life time