Sony Xperia L2 has recently received an update along with Xperia XA2 series. Whereas XA2 series received latest security patch, but the update not bring any Security patches to Xperia L2.
Now Sony has released a new update which brings the March Security patch to Sony Xperia L2. The update changes the build number from 49.0.A.3.72 to 49.0.A.4.55.
Check update manually, Head to settings-> About -> Software update.