I guess so. It is probably orthostatic which is not dangerous but annoying. Many tall, slim young women get it (but you don't have to be either of these to have it) and usually grow out of it.
Orthostatic low RR means that your heart is not as quick as it should be in responding to your changing from (near) horizontal to vertical. As you can easily imagine pumping the blood "upwards" towards your head when you are standing is more work than when you are lying or sitting. Actually your heart just steps up its rate for a couple of seconds, you don't even notice it, but if it does not quite manage, then you get faint spells, dizziness etc. (No blood in brain). One can do training to get the heart to work in sync with the getting up and lying down. It is NOT a serious illness.