Haven't seen anything official, but this tweet from Houston Raceway goes a long way toward confirmation:
https://twitter.com/HoustonRaceway/s...40024962064384
We are finalizing plans this morning to postpone and reschedule the Mopar Express Lane NHRA SpringNationals Presented By Pennzoil, scheduled for April 17-19 to June.
Look for an official announcement from the NHRA as early as today...