Research firm comScore on Friday released its latest U.S. numbers concerning mobile market share, and Asymco’s Horace Dediu noted on Monday that there may be trouble in paradise: the number of new users who purchased an Android smartphone has steadily declined in each of the first four months of 2012. Apple’s iPhone, on the other hand, has continued to grow year-over-year while Google’s Android operating system in April registered its slowest user growth since 2009. “It’s perhaps too early to suggest that we’re seeing a slowdown in the U.S. for Android,” Dediu wrote. “Perhaps there will be a return to growth in the fall. The concern has to be that rather than seeing the net adds growing — as they have for two years with only two contiguous months of decline — Android net adds have been falling for four months.” It will be interesting to see how Android fares in the summer months, however, with the arrival of HTC’s One X and the highly anticipated Samsung Galaxy S III.