Why is my image lifted outside of its own dimensions by about 1px? -

i trying place circular image button using following styles , html:

.team-assign-pic {height: 32px; width: 32px}  <button class="team-assign" type="button">     <img alt="image" class="team-assign-pic" src="img/a1.jpg">&nbsp; treavor m. </button> 

what happening image constrained 32x32 pixel shape, it's getting "lifted" looks 1px above own positioning it's true size on page like:

{height: 33px; width: 32px} 

screenshot of issue

this bit tricky me verbally explain i've attached image - subtle, it's driving me crazy!

how keep "lifting" above own size , position?