STAD results show DB req time greater than the response time

I am measuring the performance of RFC calls using STAD. After executing the RFC's (have been exposed as web services) I go to STAD and to my surprise the data base request time is greater than the response time (see below). How is this possible? Isn't the response time = CPU time + db req time + wait time? Any help will be greatly appreciated.

Response time 4,177

Time in WPs 4,177

Wait time 0

CPU Time 2,609

DB req. Time 142,597

VMC elapsed time 0