The FT-950 is okay for up to ~3:1 SWR into a purely resistive load.
Depending upon the balun and exact feedpoint, your 135' OCF is probably around 3.5:1 to 5:1 on 15m, while 30m could be twice or more that. If the internal tuner was tuning previously either band, I would suspect (up to considerable) losses in the balun and/or feedline masking the mismatch.
You are looking at an outboard tuner for those bands with your OCF, or maybe an autotuner "extender" like the MFJ-914 if you want to ballpark a match workable with the radio's internal tuner.
With room for such a large horizontal dipole, you might would fair better with a doublet and balanced feed line, though you would need an outboard tuner there as well.