You said you were landing and expect to depart again in 25 minutes, did ATC tell you, "Radar service terminated." If so the service is over and you would be on your own and no further contact required.
If they didn't then they were continuing to hold a sarwatch on you, and looking out for traffic for you and expecting you to be monitoring the ATC frequency. The "radar service terminated" is as important as "sartime cancelled", we can't just ignore you if you just disappear.
Haven't tried the service myself yet, too many CTAF in my area.