94 E320 Transmission- Help! on Vacation!

[UncleDavey]

Hi All- Drove from Atlanta to Florida Tuesday no problem- 475 miles. Went out yesterday and after 20 mile drive pulled away from a slow crawl and trans acted completely disengaged. There's no chance the shifter got bumped, and dropping to 2nd or 1st did not get car moving. Stopped, put in reverse and backed up several feet then put in drive- all well. Same problem happened again about 15 minutes later, but drove fine for another 20 miles. Transmission service was performed two weeks ago, and fluild looks fine today. I drove the car this morning and it seemed fine, but am obviously concerned since I'll be driving the family back to Atlanta on Saturday. Any thoughts?