Kissing the straps of one's tefillin

Hi,

Theoretically, one could contend that kissing the straps of one's tefillin, after donning the arm tefillin and before donning the head tefillin, would constitute an illegal interruption. However, because this does not cause a delay in donning the head tefillin, this is not a concern.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:10)

Have a great day,
Mordechai