I think you have to almost hug the thing (which isn't easy as it scans) to absorb any amount of microwave radiation to be concerned about.
If your mind still isn't at rest:
- With the tilt setting posted, the scan is going upwards so away from you
- Back scatter (e.g. off of hangar doors) attenuates the RF power
- You were under the aircraft therefore out of line of sight of the scan so it couldn't have been hitting you
Old style air intercept radars were nasty buggers with very high power RF that could hurt you. Modern weather radars put out a tiny fraction of the power of old AI radars.