Verizon in its first quarter earnings call last month noted its phone net addition figures were hurting before the introduction of unlimited data plans in February. According to the carrier, phone net additions were 398,000 in the red before its unlimited plan rolled out. After the launch of that plan, though, phone net additions rose back into the black to 109,000 for the quarter.

But could that boost already be eroding in a highly competitive wireless market? Maybe.

New data from market research firm Civic Science indicates Verizon started the second quarter off strong, enjoying a rebound in April subscriber growth compared to its first quarter figures. Civic Science CEO John Dick noted the firm recorded an uptick in the number of people who identified Verizon as their wireless carrier during the first three weeks of April in particular. And while those numbers dipped slightly in the last week of April, Dick said Verizon still came out with a net gain of around one percent.

Dick said this is the first positive month Verizon has seen in a while, but it might not last into May.

Already this week he said Verizon’s numbers have begun to trend downward. And if the numbers continue down that slippery slope, the carrier will lose whatever gains it made. For a carrier of Verizon’s size, that change could have a huge ripple effect across the industry, he said.

“A shift of even 1 percent of U.S. consumers could translate to millions of net subscriber changes,” Dick observed.

For historical context, it should be noted that the number of people who reported Verizon as their carrier to Civic Science began to dip in February, with a more noticeable drop occurring from April through October. But the carrier’s numbers turned the corner to an upswing starting in late September and early October, just after the launch of Apple’s latest iPhone. So it’s possible we could be seeing a repeat of that trend.

According to Dick, Civic Science’s data is based on a daily tracking survey online that asks people about their current wireless carrier, among other things. Around 3,000 and 4,500 U.S. residents over the age of 13 answer that question each week, he said.