It's only alarming if you ignore IDW's other releases.
On IDW's chart, they've dropped from #1 to #3 (behind TRUE BLOOD TAINTED LOVE #3 and INFESTATION #2). I, for one, expected sales to drop WAY down considering that #1 sold over 50,000 copies while IDW's top books normally sell between 10,000 to 15,000. I was hoping it would stay MUCH higher, but...ah well. C'est la vie?
What's interesting, as kitik pointed out over at Toho Kingdom, is that Godzilla #1 is at #145. They sold another 10,800 copies in April, making it IDW's sixth best-selling book for the month! The real question is, if Godzilla #1 is selling so well they needed to order over 10,000 more copies to satisfy demand in April, how is it #2 sold only 14,000 copies? Since orders are placed several months in advance (I don't know how second printing orders are placed), and considering how many people have had trouble finding #2 with how quickly it sold it in many stores, I suspect we're going to see a large second printing of Issue #2 and see it jump a bit higher in the charts next month.