I just did the same thing this past Friday...made a one pint or so starter using US-05 and DME. approx. 18 hr. lag time. I've never seen such an active fermentation. I had to remove the airlock and use a blowoff. It's Wed. night and finally starting to slow down. I really hope I'm not brewing...
My son introduced me to homebrewing then promptly moved to Japan and left all his brewing equipment here...darn. Been extract brewing for about a year and thoroughly enjoying the results.