Perhaps whiffs of radar being used by local police off the highway, or possibly NJSP driving at a distance in front of or behind you. NJSP don't run a lot of I/O. Getting constant Ka sniffs is pretty common on GSP and the NJTP though.
There’s a lot of cross traffic and overpasses and side towns too that run 34.7 .
yesterday I saw one shooting down an on ramp hiding behind trees waiting for a speeder on the highway to get in his range and field.
@lowspeed which detector are you using? My gen 2 is extremely sensitive to 34.7 and I get a lot of weak blips on the turnpike and garden state parkway. There's a lot of locals off the highways that run radar so your detector can be picking them up as well.