Sleep Mode with increased current draw after PIN Interrupt

Hi, I am using 3172 with latest 3.5.3 firmware. Loop goes into sleep when everything done and wakes up regularly for the heartbeat. I use external pins with attachInterrupt() which works fine. However, my OTII power consumption tester shows a dramatically increased power consumption once the interrupt fired. Its some 10uA in deep sleep but going back from ISR it is about 350 uA. Only wakeup in main loop with api.system.sleep.all(); brings power consumption back to normal <10uA level. I added api.system.sleep.all() at the end of the ISR but no effect. Any other hint for the problem ?

Updating to 3.5.3 fixed the problem.