Mathjax weird rendering

I have the following snippet in a note:

C_\Gamma &= \int_A^B\vec E\cdot\d\vec l &= \int_1^B\frac q{4\pi\varepsilon_0}\frac{\vec{e_r}\cdot\d\vec l}{r^2}\\
 &= \frac q{4\pi\varepsilon_0}\int_A^B\frac{\d r}{r^2} &= \frac q{4\pi\varepsilon_0}\left(\frac1{r_A}-\frac1{r_B}\right)

I expect all the equal signs to align properly. Instead, I get this:


I don’t understand why there is a white spacing that suddenly pops out of nowhere… If I remove the second ampersands of each line (ie. I don’t align the second equal), it does what one would expect. Any idea?