Can't get rid of Overfull \hbox warning using minipage

Question

I was given a template of a title page that uses minipage to position some text and logos. Unfortunately it throws Overfull \hbox warnings, that I can't get rid of.
I broke it down to the following MWE:

\documentclass{article}
\begin{document}
\parindent 0em
\LARGE\textbf{Long title of my thesis which will pro\-ba\-bly be a little bit more than one line}
\vspace{24pt}\\
by\\
My Name \\[1.5cm]
\begin{minipage}{0.4\textwidth}
    \begin{flushleft} \large
      \LARGE\textbf{A}\\
      \LARGE February
    \end{flushleft}
  \end{minipage}
  \begin{minipage}{0.6\textwidth}
    \begin{flushright}
      \LARGE\textbf{B}\\
      \LARGE March
    \end{flushright}
  \end{minipage}
\end{document}

I tried changing this using \sloppy and \fussy with no success. Also there is another overfull \hbox warning with my title. I tried getting rid of that one using hyphenation as shown in the MWE, but as you can see, I wasn't successfull here either.
Since I was given this template, I don't want to change the output significantly, but I don't want to keep getting this warning. Why is this snippet throwing the \hbox warning and how can I fix it?

Answer 1

You can use \overfullrule=5pt to see where the overfull box is:

and the problem is that you have two minipages that sum \textwidth separated by 1 space (the new line at the end of the first). Just using a comment solve it:

\documentclass{article}
\overfullrule=5pt
\begin{document}
\parindent 0em
\LARGE\textbf{Long title of my thesis which will pro\-ba\-bly be a little bit more than one line}
\vspace{24pt}\\
by\\
My Name \\[1.5cm]
\begin{minipage}{0.4\textwidth}
    \begin{flushleft} \large
      \LARGE\textbf{A}\\
      \LARGE February
    \end{flushleft}
  \end{minipage}% <---- HERE 
  \begin{minipage}{0.6\textwidth}
    \begin{flushright}
      \LARGE\textbf{B}\\
      \LARGE March
    \end{flushright}
  \end{minipage}
\end{document}